Index: src/wp-admin/css/common.css
===================================================================
--- src/wp-admin/css/common.css	(revision 33568)
+++ src/wp-admin/css/common.css	(working copy)
@@ -712,6 +712,7 @@
 .postbox .hndle,
 .stuffbox .hndle,
 .control-section .accordion-section-title,
+.control-section .was-accordion-section-title,
 .sidebar-name,
 #nav-menu-header,
 #nav-menu-footer,
@@ -2959,7 +2960,8 @@
 	background: #fff;
 }
 
-.accordion-section-title {
+.accordion-section-title,
+.was-accordion-section-title {
 	margin: 0;
 	padding: 12px 15px 15px;
 	position: relative;
@@ -2999,7 +3001,8 @@
 	display: none;
 }
 
-.control-section .accordion-section-title {
+.control-section .accordion-section-title,
+.control-section .was-accordion-section-title {
 	border-left: none;
 	border-right: none;
 	padding: 10px 10px 11px 14px;
Index: src/wp-admin/css/customize-controls.css
===================================================================
--- src/wp-admin/css/customize-controls.css	(revision 33568)
+++ src/wp-admin/css/customize-controls.css	(working copy)
@@ -57,7 +57,8 @@
 	margin-bottom: 15px;
 }
 
-#customize-controls .customize-info .accordion-section-title {
+#customize-controls .customize-info .accordion-section-title,
+#customize-controls .customize-info .was-accordion-section-title {
 	background: #fff;
 	color: #555;
 	border-left: none;
@@ -383,7 +384,8 @@
 	display: block;
 }
 
-.panel-meta.customize-info .accordion-section-title {
+.panel-meta.customize-info .accordion-section-title,
+.panel-meta.customize-info .was-accordion-section-title {
 	margin-left: 48px;
 }
 
Index: src/wp-admin/css/customize-nav-menus.css
===================================================================
--- src/wp-admin/css/customize-nav-menus.css	(revision 33568)
+++ src/wp-admin/css/customize-nav-menus.css	(working copy)
@@ -686,11 +686,11 @@
 
 #available-menu-items .accordion-section-title .no-items,
 #available-menu-items .cannot-expand .accordion-section-title .spinner,
-#available-menu-items .cannot-expand .accordion-section-title > button {
+#available-menu-items .cannot-expand .accordion-section-title button {
 	display: none;
 }
 
-#available-menu-items-search.cannot-expand .accordion-section-title .spinner {
+#available-menu-items-search.cannot-expand .was-accordion-section-title .spinner {
 	display: block;
 }
 
@@ -813,12 +813,12 @@
 }
 
 #available-menu-items .accordion-section-title.loading .spinner,
-#available-menu-items-search.loading .accordion-section-title .spinner {
+#available-menu-items-search.loading .was-accordion-section-title .spinner {
 	visibility: visible;
 	margin: 0 20px;
 }
 
-#available-menu-items-search .clear-results {
+#available-menu-items-search .was-accordion-section-title .clear-results {
 	position: absolute;
 	top: 20px;
 	right: 20px;
Index: src/wp-admin/customize.php
===================================================================
--- src/wp-admin/customize.php	(revision 33568)
+++ src/wp-admin/customize.php	(working copy)
@@ -152,7 +152,7 @@
 					<span class="preview-notice"><?php
 						echo sprintf( __( 'You are customizing %s' ), '<strong class="panel-title site-title">' . get_bloginfo( 'name' ) . '</strong>' );
 					?></span>
-					<button class="customize-help-toggle dashicons dashicons-editor-help" aria-expanded="false"><span class="screen-reader-text"><?php _e( 'Help' ); ?></span></button>
+					<button type="button" class="customize-help-toggle dashicons dashicons-editor-help" aria-expanded="false"><span class="screen-reader-text"><?php _e( 'Help' ); ?></span></button>
 				</div>
 				<div class="customize-panel-description"><?php
 					_e( 'The Customizer allows you to preview changes to your site before publishing them. You can also navigate to different pages on your site to preview them.' );
Index: src/wp-admin/js/customize-controls.js
===================================================================
--- src/wp-admin/js/customize-controls.js	(revision 33568)
+++ src/wp-admin/js/customize-controls.js	(working copy)
@@ -527,7 +527,7 @@
 			var section = this;
 
 			// Expand/Collapse accordion sections on click.
-			section.container.find( '.accordion-section-title, .customize-section-back' ).on( 'click keydown', function( event ) {
+			section.container.find( '.accordion-section-title[tabindex="0"], .customize-section-back' ).on( 'click keydown', function( event ) {
 				if ( api.utils.isKeydownButNotEnterEvent( event ) ) {
 					return;
 				}
@@ -1124,7 +1124,7 @@
 			var meta, panel = this;
 
 			// Expand/Collapse accordion sections on click.
-			panel.container.find( '.accordion-section-title' ).on( 'click keydown', function( event ) {
+			panel.container.find( '.accordion-section-title[tabindex="0"]' ).on( 'click keydown', function( event ) {
 				if ( api.utils.isKeydownButNotEnterEvent( event ) ) {
 					return;
 				}
@@ -1149,11 +1149,7 @@
 
 			meta = panel.container.find( '.panel-meta:first' );
 
-			meta.find( '> .accordion-section-title .customize-help-toggle' ).on( 'click keydown', function( event ) {
-				if ( api.utils.isKeydownButNotEnterEvent( event ) ) {
-					return;
-				}
-				event.preventDefault(); // Keep this AFTER the key filter above
+			meta.find( '.customize-help-toggle' ).on( 'click', function() {
 
 				meta = panel.container.find( '.panel-meta' );
 				if ( meta.hasClass( 'cannot-expand' ) ) {
@@ -1231,7 +1227,8 @@
 				overlay = section.closest( '.wp-full-overlay' ),
 				container = section.closest( '.wp-full-overlay-sidebar-content' ),
 				siblings = container.find( '.open' ),
-				topPanel = overlay.find( '#customize-theme-controls > ul > .accordion-section > .accordion-section-title' ),
+				// Get the accordion sections but not the Active Theme section.
+				topPanel = overlay.find( '#customize-theme-controls > ul > .accordion-section:not(.control-section-themes)	 > .accordion-section-title' ),
 				backBtn = section.find( '.customize-panel-back' ),
 				panelTitle = section.find( '.accordion-section-title' ).first(),
 				content = section.find( '.control-panel-content' );
@@ -3059,11 +3056,7 @@
 		});
 
 		// Expand/Collapse the main customizer customize info.
-		$( '.customize-info' ).find( '> .accordion-section-title .customize-help-toggle' ).on( 'click keydown', function( event ) {
-			if ( api.utils.isKeydownButNotEnterEvent( event ) ) {
-				return;
-			}
-			event.preventDefault(); // Keep this AFTER the key filter above
+		$( '.customize-info' ).find( '.customize-help-toggle' ).on( 'click', function() {
 
 			var section = $( this ).closest( '.accordion-section' ),
 				content = section.find( '.customize-panel-description:first' );
Index: src/wp-admin/js/customize-nav-menus.js
===================================================================
--- src/wp-admin/js/customize-nav-menus.js	(revision 33568)
+++ src/wp-admin/js/customize-nav-menus.js	(working copy)
@@ -138,15 +138,8 @@
 			} );
 
 			// Clear the search results.
-			$( '.clear-results' ).on( 'click keydown', function( event ) {
-				if ( event.type === 'keydown' && ( 13 !== event.which && 32 !== event.which ) ) { // "return" or "space" keys only
-					return;
-				}
-
-				event.preventDefault();
-
+			$( '.clear-results' ).on( 'click', function( event ) {
 				$( '#menu-items-search' ).val( '' ).focus();
-				event.target.value = '';
 				self.search( event );
 			} );
 
@@ -202,17 +195,13 @@
 				$otherSections.fadeOut( 100 );
 				$searchSection.find( '.accordion-section-content' ).slideDown( 'fast' );
 				$searchSection.addClass( 'open' );
-				$searchSection.find( '.clear-results' )
-					.prop( 'tabIndex', 0 )
-					.addClass( 'is-visible' );
+				$searchSection.find( '.clear-results' ).addClass( 'is-visible' );
 			} else if ( '' === event.target.value ) {
 				$searchSection.removeClass( 'open' );
 				$otherSections.show();
-				$searchSection.find( '.clear-results' )
-					.prop( 'tabIndex', -1 )
-					.removeClass( 'is-visible' );
+				$searchSection.find( '.clear-results' ).removeClass( 'is-visible' );
 			}
-			
+
 			this.searchTerm = event.target.value;
 			this.pages.search = 1;
 			this.doSearch( 1 );
Index: src/wp-includes/class-wp-customize-nav-menus.php
===================================================================
--- src/wp-includes/class-wp-customize-nav-menus.php	(revision 33568)
+++ src/wp-includes/class-wp-customize-nav-menus.php	(working copy)
@@ -713,12 +713,12 @@
 				</h3>
 			</div>
 			<div id="available-menu-items-search" class="accordion-section cannot-expand">
-				<div class="accordion-section-title">
+				<div class="was-accordion-section-title">
 					<label class="screen-reader-text" for="menu-items-search"><?php _e( 'Search Menu Items' ); ?></label>
 					<input type="text" id="menu-items-search" placeholder="<?php esc_attr_e( 'Search menu items&hellip;' ) ?>" aria-describedby="menu-items-search-desc" />
 					<p class="screen-reader-text" id="menu-items-search-desc"><?php _e( 'The search results will be updated as you type.' ); ?></p>
 					<span class="spinner"></span>
-					<span class="clear-results"><span class="screen-reader-text"><?php _e( 'Clear Results' ); ?></span></span>
+					<button type="button" class="clear-results not-a-button"><span class="screen-reader-text"><?php _e( 'Clear Results' ); ?></span></button>
 				</div>
 				<ul class="accordion-section-content" data-type="search"></ul>
 			</div>
Index: src/wp-includes/class-wp-customize-panel.php
===================================================================
--- src/wp-includes/class-wp-customize-panel.php	(revision 33568)
+++ src/wp-includes/class-wp-customize-panel.php	(working copy)
@@ -366,13 +366,13 @@
 	protected function content_template() {
 		?>
 		<li class="panel-meta customize-info accordion-section <# if ( ! data.description ) { #> cannot-expand<# } #>">
-			<button class="customize-panel-back" tabindex="-1"><span class="screen-reader-text"><?php _e( 'Back' ); ?></span></button>
+			<button type="button" class="customize-panel-back" tabindex="-1"><span class="screen-reader-text"><?php _e( 'Back' ); ?></span></button>
 			<div class="accordion-section-title">
 				<span class="preview-notice"><?php
 					/* translators: %s is the site/panel title in the Customizer */
 					echo sprintf( __( 'You are customizing %s' ), '<strong class="panel-title">{{ data.title }}</strong>' );
 				?></span>
-				<button class="customize-help-toggle dashicons dashicons-editor-help" tabindex="0" aria-expanded="false"><span class="screen-reader-text"><?php _e( 'Help' ); ?></span></button>
+				<button type="button" class="customize-help-toggle dashicons dashicons-editor-help" aria-expanded="false"><span class="screen-reader-text"><?php _e( 'Help' ); ?></span></button>
 			</div>
 			<# if ( data.description ) { #>
 				<div class="description customize-panel-description">
@@ -458,7 +458,7 @@
 			<button type="button" class="customize-panel-back" tabindex="-1">
 				<span class="screen-reader-text"><?php _e( 'Back' ); ?></span>
 			</button>
-			<div class="accordion-section-title">
+			<div class="was-accordion-section-title">
 				<span class="preview-notice">
 					<?php
 					/* Translators: %s is the site/panel title in the Customizer. */
Index: src/wp-includes/class-wp-customize-section.php
===================================================================
--- src/wp-includes/class-wp-customize-section.php	(revision 33568)
+++ src/wp-includes/class-wp-customize-section.php	(working copy)
@@ -352,7 +352,7 @@
 			<ul class="accordion-section-content">
 				<li class="customize-section-description-container">
 					<div class="customize-section-title">
-						<button class="customize-section-back" tabindex="-1">
+						<button type="button" class="customize-section-back" tabindex="-1">
 							<span class="screen-reader-text"><?php _e( 'Back' ); ?></span>
 						</button>
 						<h3>
@@ -413,7 +413,7 @@
 				}
 				?>
 
-				<button type="button" class="button change-theme" tabindex="0"><?php _ex( 'Change', 'theme' ); ?></button>
+				<button type="button" class="button change-theme"><?php _ex( 'Change', 'theme' ); ?></button>
 			</h3>
 			<div class="customize-themes-panel control-panel-content themes-php">
 				<h3 class="accordion-section-title customize-section-title">